The invention is in the field of systems for altering the temperature of structures such as houses or commercial buildings, particularly for cooling human-occupied structures.
Standard home or commercial interior cooling systems rely heavily on air-conditioning units. In some areas of the country, evaporative coolers have become popular. The primary advantage of evaporative cooling is that it operates at significantly lower power than air-conditioning systems, but the primary disadvantage is that it is suitable for use only in dry (non-humid) weather. Thus, it is now common for evaporative cooling systems to have an air-conditioning backup. However, such dual systems are often expensive, because each "half" of the system must have the capacity to cool the entire structure without assistance from the other component.
In addition, a great deal of the cooling power of standard interior cooling systems is wasted by offsetting heat infiltration across particular areas of the structure that allow a high thermal gradient, such as windows, doors, and skylights. Thus, much of the cooling power of standard systems is wasted.
One prior art system, disclosed in U.S. Pat. No. 3,964,268, issued Jun. 22, 1976, to DiPeri, discloses an evaporative-cooling system that solves some, but not all, of the above-described problems. DiPeri discloses an evaporative cooler with two sets of ducts, one for cooling the interior of the structure and the other for flowing evaporatively cooled air along the exterior surface of the roof, to reduce the infiltration of heat from solar energy impinging on that surface. However, the DiPeri system does not apply the exterior air selectively, and so the amount of exterior cooling required to reduce heat infiltration is quite high. Thus, DiPeri-type systems excessively cool the outside air and therefore still require a large expenditure of total energy. Other systems apply evaporative cooling to spaces outside and adjacent to the structure, but such systems also do not apply the exterior cooling selectively.